1. Field of the Invention
The present invention relates to a liquid crystal display (LCD) panel and a method for adjusting voltage applied in the LCD panel; and particularly to an LCD panel with a reduced flicker effect, and a method for adjusting voltage applied in the LCD panel in order to reduce or even eliminate any flicker effect.
2. General Background
Generally, one well-known major disadvantage of cathode ray tube (CRT) monitors is the flicker problem. Liquid crystal display (LCD) monitors can also exhibit the flicker problem. In practice, a user is liable to be inconvenienced or annoyed by the flicker problem no matter which kind of monitor he or she has.
The reason for the occurrence of the flicker problem in an LCD monitor is as follows. To illustrate why an LCD panel flickers, suppose that a manufactured LCD panel has a common voltage (Vcom) of 5.5V according to its specifications. If an input video signal varies between 0V and 10V, the full-scale voltage applied to different electric fields of the pixel-based graphic display varies accordingly. In one field, the full-scale voltage may be 4.5V; and in another field, the full-scale voltage may be 5.5V. This difference in full-scale voltage translates to a difference in light intensity, which is perceived as flicker by a viewer.
In mass manufacturing, due to the variations in the construction of each LCD panel, the optimal Vcom voltage can differ from LCD panel to LCD panel or even across a single LCD panel. Original equipment manufacturers must therefore adjust each of the LCD panels coming out of the factory to eliminate flicker. For small LCD screens where the backplane of the LCD panel can be considered as a low-impedance ground, a single potentiometer can be connected to the LCD panel for adjustment of the common voltage. Traditionally, the potentiometer is manually connected to the LCD panel, and the adjustment is performed by a human operator. However, this procedure has low precision, and the LCD panel is liable to be accidentally damaged by the operator. In addition, the procedure is generally only suitable for small LCD panels. Furthermore, due to human error in viewing the displayed image, the flicker problem may still occur in the LCD panel even after meticulous adjustment by the operator.
What is needed, therefore, is a liquid crystal display panel and a method for adjusting voltage applied in a liquid crystal display panel which can overcome the above-described problems.